Sist/mbrium,] CRUCIFER.E. 



63 



■ 



pedlcello quintiipio longioribus tereti- torulosis pubescentibus,— S. humile. Ledebour^ 

 MSS. ined, 



«, Ledeh, ; foliis subintegris. 



^. Ledeb,; foliis sinuato-dentatis subpinnatifidis. 



Radix sublonge descendens, anguste fusiformis, perennis. Caules rarius solitarii, saepissirae plurimi ex 

 eadem radice, palmares, diffusi, nunc prosfrati, simplices vel superne ramosi, pubescenti-hirsuti, non raro pur- 

 pureo tincti. Folia omnia magis minusve pubescenti-incana, pube ramosa, versus basin pllis imraixta ; in 

 a. subintegra, in |3. sinuato-dentata, etiani dentato-pinnatifida ; radicalia oblongo-spathulata, obtusa ; caulina 

 lanceolata, etiani obtusa, rarius subacuta, basi in petiolum attenuata. Flores in coryrabis parvis terminalibus, 

 majusculi, albi vel pallide purpureo-rosei. PcdiceUi calycem subsequantes. CaJt/x pubescenti-hirtus, pilis 

 ad apicem longioribus; sepalis late ovatis, concavis, erectis. Petala calycc plusquam dupio longlora, 

 unguiculata, limbo lato, patente, subretuso. Pistillum : germen cylindraceum, valde pubescens : Stigma sub- 

 sessile, obtusum, vix capitatum. Siliqum in racemis triuncialibus, pollicem long?e, subcurvata^, lincares, tcretes, 

 torulosse, pubescentes, in acumen breve terminantes. Semina uniserialia, ovalia, fusca. Cotyledones 

 incumbentes. 



Hab. a. Rocky Mountains, between lat. 52° and 57'='. Bmmmond,—;^. About the Maclvenzie River, 

 from lat, 60° to 68°. 7)r. Richardson. Drummond. — -Tbis plant has so entirely the habit of some states of 

 Arabis petrcBOj that, were it not for the more rounded and toriilose pods, I should probably not have ventured 

 to separate them. An examination of the seeds, however, soon convinced me that the plant must be far 

 removed from the genus Arabis, as it now stands; and on comparing it with my specimens of Sisymbrium 

 humile, communicated hy Professor Ledebour, from the Altai, I find them in every respect to correspond; 

 and the two varieties of our North American Travellers precisely agree with the a. and 0, of that excellent 

 Botanist, 



8. S. arahidoides; annuum, foliis radicalibus lyrato-pinnatifidis subhirsutis, caulinis linear- 

 ibus integerrimis cauleque erecto ramose glaberrimis, siliquis erectis linearibus strictis 

 pedicello duplo longioribus, (Tab. XXI,) — Arabis lyrata. Linn. Sp, PL p. 929. Purskj 

 FL Am. V. 2. p. 437. De Cand. Prodr. v. I. p. 146. Rich, in FrankL '[st Journ. ed, 2. Jpp, 

 p. 26. — (These syns. to be expunged from A. petraa, p. 42 of this work.) 



Radix parva, annua, subfusiforrais. Caules erecti, spitharasei et ultra, solitarii, vel plurimi ex eadem radice, 

 glabri, subglauci, flexuosi, ramosi. Folia radicalia unciam duas tres uncias longa, in rosulam expausa, lyrato- 

 pinnatifida, lobis brevibus inferioribus acutis, parce pilosa, Caulina linearia, subunciam louga, integerrima, 

 omnia magis minusve inferne in petiolum attenuata, Pedicelii floris longitudine, glaberrimi. Calyx 

 omnino glaber, foliolis ovatis, Petala oblongo-obovata, calyce plusquam duplo longlora, alba vel purpuras- 

 centia. SHiqua sesquiunciam fere ad duas uucias longa, pedicello duplo longior, erecta, stricta, anguste 

 linearis, stylo brevi terminata. Stigma parvum, capitatum. Semina uniserialia, ovalia, rufo-fusca. Cotyle- 

 dones incumbentes. 



Hab. Common on the bants of rivers, from Canada to lat. 68°, and in dry or waste places. Dr. Richardson. 

 —Numerous specimens of tbis plant are in Dr. Richardson's collection, with flowers and fruit At first I bad 

 referred it to what I then considered a variety of A. petraa, the A. lyrata of Linn. lu this opinion 

 I feel almost sure I am correct, and hence I have adopted that synonym above. But the cotyledons 

 are decidedly incumbent, and the root is annual Besides these important characters, by which our plant 

 may be known from A. petra>a, I find its pods io be more upright, longer, and straighter, especially when 

 perfect. In other respects, particularly in the form of its leaves, and the size and appearance of its flowers, 

 the two are almost identical. Linnspus well observes of his Arabis lyrata, " Statura et habitus A. thalianm, 

 prseter quod folia radicalia lyrata, glabra et flores majores." And Arnbis thaliana is equally a Sisymbrium 

 having incumbent co/'^/edons.— Whether or not the Arabis ambigua of De Candolle, and Chamisso, and 



